Barrier islands on bedrock: a new landform type demonstrating the role of antecedent topography on barrier form and evolution

J.A.G. Cooper, D.W.T. Jackson, A.G. Dawson, S. Dawson, C.R. Bates, W. Ritchie

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Barrier islands commonly occur in coastal plain and deltaic settings, and a variety of behavioral and stratigraphic models exist. In this paper, a 90 km long barrier island system in the Outer Hebrides of Scotland is identified for the first time. Uniquely among barrier islands, the system rests directly on a planar bedrock (gneiss) surface (a strandflat). This bedrock surface has a profound influence on the morphology of the barrier island chain, and exerts the dominant influence on barrier island form and evolution during transgression. Topographical irregularities on the bedrock surface control both plan and profile morphology of the barrier islands. Under sea-level rise, by barrier migration, sediment is redistributed onshore and alongshore in a strongly three-dimensional manner, determined by topographic variability in the bedrock. The barrier islands represent an endpoint in transgressive barrier island geomorphology that is controlled by the bedrock surface: they are at the upper end of the recognized tidal amplitude for barrier islands; the offshore wave regime is very high-energy; they lack a shoreface; and neither ravinement surface nor transgressive sand sheet are developed. Sediment supply is dominated by offshore-derived skeletal carbonate.

Original languageEnglish
Pages (from-to)923-926
Number of pages4
JournalGeology
Volume40
Issue number10
Early online date23 Jul 2012
DOIs
Publication statusPublished - Oct 2012

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